Mitogen-activated Protein Kinase Phosphatase-1 (MKP-1) Expression Is Induced by Low Oxygen Conditions Found in Solid Tumor Microenvironments

doi:10.1074/jbc.274.18.12890

Mitogen-activated Protein Kinase Phosphatase-1 (MKP-1) Expression Is Induced by Low Oxygen Conditions Found in Solid Tumor Microenvironments

A CANDIDATE MKP FOR THE INACTIVATION OF HYPOXIA-INDUCIBLE STRESS-ACTIVATED PROTEIN KINASE/c-Jun N-TERMINAL PROTEIN KINASE ACTIVITY*

From the ^‡Pharmaceutical Discovery Division, SRI International, Menlo Park, California 94025, the ^¶Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, and the ^‖Vollum Institute and Department of Pathology, Oregon Health Sciences University, Portland, Oregon 97201

Abstract

Pathophysiological hypoxia is an important modulator of gene expression in solid tumors and other pathologic conditions. We observed that transcriptional activation of the c-jun proto-oncogene in hypoxic tumor cells correlates with phosphorylation of the ATF2 transcription factor. This finding suggested that hypoxic signals transmitted to c-jun involve protein kinases that target AP-1 complexes (c-Jun and ATF2) that bind to its promoter region. Stress-inducible protein kinases capable of activating c-jun expression include stress-activated protein kinase/c-Jun N-terminal protein kinase (SAPK/JNK) and p38 members of the mitogen-activated protein kinase (MAPK) superfamily of signaling molecules. To investigate the potential role of MAPKs in the regulation of c-jun by tumor hypoxia, we focused on the activation SAPK/JNKs in SiHa human squamous carcinoma cells. Here, we describe the transient activation of SAPK/JNKs by tumor-like hypoxia, and the concurrent transcriptional activation of MKP-1, a stress-inducible member of the MAPK phosphatase (MKP) family of dual specificity protein-tyrosine phosphatases. MKP-1 antagonizes SAPK/JNK activation in response to diverse environmental stresses. Together, these findings identify MKP-1 as a hypoxia-responsive gene and suggest a critical role in the regulation of SAPK/JNK activity in the tumor microenvironment.

Footnotes

↵* This work was supported by Grants CA73807, CA20329, and CA67166 from the National Cancer Institute.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵§ To whom correspondence should be addressed: Pharmaceutical Discovery Div., SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025. Tel.: 650-859-3080; Fax: 650-859-5816; E-mail: keith.laderoute{at}sri.com.
↵2 K. R. Laderoute, H. L. Mendonca, J. M. Calaoagan, and A. M. Knapp, unpublished data.
Abbreviations:

ATF2

activating transcription factor 2, SAPK/JNK, stress-activated protein kinase/c-Jun N-terminal protein kinase

MAPK

mitogen-activated protein kinase

ERK

extracellular signal-regulated kinase

GST

glutathioneS-transferase

PBS

phosphate-buffered saline

PBS-T

PBS with Tween 20

MKP

MAPK phosphatase

TPA

12-O-tetradecanoylphorbol-13-acetate

PTK

protein-tyrosine kinase

PMSF

phenylmethylsulfonyl fluoride

DTT

dithiothreitol

TES

N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid
- Received November 3, 1998.
- Revision received January 8, 1999.
The American Society for Biochemistry and Molecular Biology, Inc.